Characterizing the Terroir of Niagara: What Causes Regional Differences in Wine?

Many of you reading this blog are already familiar with the concept of terroir. In very basic terms, terroir is a term which encompasses the unique characteristics of a wine as formed by various influences, including grape variety, environment, climate, and vineyard management practices. While some think terroir can be defined by one single cause, it is likely that a combination of many different factors influence the exact sensory profile of the wine, even if a many of the factors are similar between vineyard sites. The combination of historical factors in addition to current practices may very well all blend together to produce what we think of as terroir in a wine. Many countries throughout the world have embraced the concept of terroir in order to help distinguish different winemaking regions within their borders and to promote uniqueness of their wines compared with all others.

Today we’re going to focus on a study that attempted to define the terroir of the Niagara Peninsula region of Canada. There have been a lot of studies focusing on terroir in different wine regions in Europe, however, few have been performed in America, and even fewer in many Canadian wine regions. In the Niagara Peninsula, there have been at least three different viticultural areas that have been defined by certain sensory difference, though it is not known exactly

how the soil or environmental interact to produce these sensory differences.

The study today aimed to examine whether or not soil characteristics are the most important influencers of terroir, or if a combination of factors (including human intervention/vineyard management practices) all together result in unique wines of a particular region. Specifically, the study examined the effects of vine vigor and soil texture on terroir, which could potentially provide information regarding to the choice of future vineyard sites as well as specific vineyard management practices to make the best of the terroir of the region.

Methods

5 Chardonnay vineyard sites were included in this study: 2 from the Niagara-on-the-Lake region, 2 from the Lakeshore Plain region, and 1 located on the Niagara Escarpment near Vineland. All 5 sites were quite variable in terms of their soil type, texture, grape yield, and vine size.

GPS (global positioning system) was used to determine the shapes and sizes of the vineyard blocks, as well as to create the soil texture maps and to locate the sentinel vines for data collection.

3cm x 75cm soil samples were collected near each vine and the following analyses were performed on each sample: elemental concentration, cation exchange capacity, base saturation, pH, and organic matter concentration. The proportion of sand, silt, and clay were also determined and then entered into GIS (geographic information system) software to virtually construct the soil texture and composition maps for each vineyard block.

Sites were selected that had common rootstocks, clones, training systems, and vineyard management practices in order to minimize the number of confounding factors in the study.

For climate data, rainfall and growing degree days from veraison to harvest was collected from Niagara Agricultural Weather Network stations near each vineyard block.

Vines were determined to be either “high vine size” or “low vine size” depending upon the weight of the cane prunings per vine during winter pruning.

After harvesting the grapes, wine was made from each vine size x soil texture combination (two replicates per combination) and made using standard enological practices (if you want specifics, just ask).

For each wine must, the following were measured and analyzed: Brix, titratable acidity, and pH.

For each finished wine, the following were measured and analyzed: titratable acidity, pH, ethanol content, and total phenols.

Sensory analyses were performed 3 months after bottling in 1999, 8 months after bottling in 2000, and 3 months after bottling in 2001. The panel included 12 faculty, staff, and students from Brock University and was the same for all three years. The age range of the panelists was 22 to 48 years, and all had extensive wine tasting experience. Wine was tasting in six 1-hour sessions. Panelists evaluated each wine for intensity of aroma and flavor and were presented to the panelists in two random flights of 4 wines each with a 2 minute break in between each flight.

Results/Conclusions

Due to the extremely detailed and lengthy nature of the results, I’m going to present them in summary form instead of the usual bullet point detail, but if you have specific questions or want more details from one particular result or another, please ask and I’ll see what I can find.

Soil texture appeared to have some influence on the wines from the different Niagara regions, though from one vintage to the next, results were inconsistent. The general trend, however, was that soils rich in clay textures produced wines that possessed more vegetal, earthy, and citrus characteristics while soils rich in sandy textures produced wines that possessed more floral and melon characteristics. It is important to note that these general trends were not consistent from vintage to vintage, though overall they were the most common characteristics noted over the entire 3 year period.

In general the size of the vines did not seem to have an influence on the chemical composition of the musts nor the wines, though it was noted that high vine size did seem to increase Brix levels in all three locations in the 2001 vintage. In terms of sensory characteristics, there didn’t seem to be any relationship between vine size and any particular aromas or flavors.

The vintage effect was significant for wine quality at all three sites. Specifically, environmental conditions for each vintage were markedly different, thus resulting in big differences in wine quality between each site each year. One of the most variable environmental conditions from vintage to vintage was the level of precipitation: in 1999, precipitation ranged from 420 to 569mm; in 2000 the range was from 547 to 695mm; and finally in 2001 the range was from 325 to 518mm. In terms of sensory characteristics, wines from the 2000 vintage tended to show more vegetal and earthy aromas as well as higher acidity, while the wines from the 2001 showed more floral and melon characteristics.

The vineyard site location effect was clear over all three vintages. The wines from each of the three sites were clearly different from one another for all three vintages in terms of their chemical and sensory characteristics and while there was significant variation at each site from year to year, general trends appeared to be consistent. According to the authors (and I tend to agree), these differences were due to the “mesoclimate” of each site. Specifically, each site experienced a

different number of growing degree days as well as different levels of precipitation. Those sites that were closer to the lake tended to have cooler growing degree days, while those sites more inland tended to have slightly warmer growing degree days (makes sense to me).

Overall, wines from vineyard sites in the Niagara Lakeshore region tended to have greater intensities of vegetal, earthy, and citrus aromas and flavors, while wines from vineyard sites in the Escarpment region tended to have more melon and floral aromas and flavors. The site at the Lakeshore Plain location was the only site out of the 5 that displayed significant effects of both soil texture and vine size during all vintages.

In conclusion, while the study found differences between sites and differences between vintages, there was no clear reason found as to why the sites differed in terms of their chemical and sensory characteristics. For the most part, soil type and vine size didn’t really have much of an effect on their own, so there must be something else going on that contributes to the overall terroir of the wines of a given reason. If you ask me, what I think it going on is a synergistic effect of a multitude of characteristics at each site effectively working together to create a completely unique style of wine that can’t be truly replicated anywhere else. Maybe soil type by itself doesn’t affect terroir differences in wine, but perhaps soil type plus environmental conditions plus vineyard management technique, plus maybe even the local flora and fauna in the area all work together to create a unique wine or terroir that is significantly different from site to site.

In general, this study provides a great deal of information on defining the terroir of the Niagara region of Canada. While the results were somewhat inconclusive in terms of exactly what “causes” the unique terroir of the region, this study does provide good insight into what the predominant characteristics of Niagara region are as well as information that could help the next researchers develop this question further. What exactly gives the terroir of the Niagara region (or any region for that matter)? I think we’ll discover there isn’t one single thing, and that it’s a combination of perhaps innumerable things that result in the uniqueness of the wines from any given region. Now that we have an idea of what the general characteristics are for Chardonnay of the region, vineyard managers and winemakers working in that region may be able to utilize this information to optimize their growing, harvesting, and winemaking strategies of the Chardonnay in order to bring out the best of Niagara. Certainly, a lot more work needs to be done (including work on more than one variety of grape!), but I think this study is a great start!

What do you all think of this topic? For those familiar with Niagara wines, do these results “make sense” to you? Or not? Please feel free to leave any and all comments!

Source: Reynolds, A.G., Taylor, G., and de Savigny, C. 2013. Defining Niagara Terroir by Chemical and Sensory Analysis of Chardonnay Wines from Various Soil Textures and Vine Sizes. American Journal of Enology and Viticulture 64(2): 180-194.